Reliable source high quality Masur / Karelian Birch lumber?

I am looking for a very reliable source (prefer domestic, but overseas OK), from which to obtain highly figured Masur / Karelian Birch. I spent quite a bit of time online and found several veneer sources, a few places that purportedly sell the lumber, but the pieces shown were really slim pickings. I also realize there are some eBay sellers, however I am looking for larger planks that I can reduce myself.